U.S. patent application Ser. No. 705,330 filed Feb. 25, 1985 now U.S. Pat. No. 4,628,824 and assigned to the assignee of the present invention illustrates a self-steering powered locomotive railway truck arrangement. An illustrated embodiment has a frame supported on wheel and axle assemblies by a primary suspension arrangement utilizing conventional frame attached pedestals which limit the lateral and steering motions of axle mounted journal boxes interconnected by a steering linkage. The axles are individually driven by traction motors supported by the axles and the frame which also carries a brake system having wheel tread engaging shoes, linkage and associated actuating cylinders.
While the application of railway trucks having steerable or self-steering axles has been widely proposed and to some extent applied during recent years, the application of steerable axle concepts to powered locomotive trucks and the like is less far advanced. The use of pedestal guided journal boxes in primary suspensions of nonsteerable axle railway locomotive trucks is common practice. However systems without pedestals are also known as shown for example in U.S. Pat. No. 3,841,232 Hess. In either case, removal of a wheel and axle assembly for replacement or service on an associated traction motor commonly requires raising the truck frame or lowering the axle a substantial distance to extend the primary suspension springs, or the like, to their uncompressed dimension, normally a considerable distance.
In addition, conventional frame mounted brake systems, while operating satisfactorily, must comply with the vertical wheel motions permitted by the primary suspension system. Further, when applied to trucks having steering axles, a brake application will introduce forces tending to return the axles to their centered positions, even though the truck may be undergoing curving action at the time.